Bridged biphospholes and metallocenes prepared therefrom

ABSTRACT

The invention relates to novel bridged biphosphole ligands according to the general formula: 
                 
 
where R 2 , R 3 , R 4  are chosen from hydrogen, alkyl, aryl or silyl, R 1  is chosen from hydrogen, alkyl, aryl or halogen, R 1  possibly being replaced with a direct bond between the two phosphorus atoms and T is a divalent group. The invention also relates to metallocenes obtained from these ligands. These metallocenes are useful as catalytic components for the polymerization of olefins.

FIELD OF THE INVENTION

The subject of the present invention is novel catalysts for polymerizingolefins.

BACKGROUND OF THE INVENTION

Catalysts based on metallocenes are known. In these organometalliccomplexes, a metal atom is sandwiched between two cyclopentadienylligands. The synthesis, structure and properties of these complexes isdescribed, for example, by Nicholas J. Long in “Metallocenes” publishedby Blackwell Science, 1998.

Ligands containing heteroatoms of the electron-donating type, such asphosphorus, are also known. Thus, cyclopentadienyl-derived ligands inwhich a carbon atom is replaced with a phosphorus atom are known. Theseligands are denoted by the term “phospholyl”.

Zirconium-based organometallic complexes comprising one or twosubstituted phospholyl ligands have been prepared. Their catalyticactivity for the polymerization of ethylene is unsatisfactory (C.Janiak, U. Versteeg, K. C. H. Lange, R. Weimann and E. hahn, Journal ofOrganometallic Chemistry 501 (1995), 219-234).

Such substituted monophospholyls or biphospholyls of the(R¹,R²,R³,R⁴,C₄P)₂ZrCl₂ type are also known, for Example from E. J. M.de Boer et al., Journal of Molecular Catalysis A: Chemistry 128 (1998),155-165. Their catalytic activity with regard to the polymerization ofpropylene has been evaluated. Only complexes with a phospholyl ligandcarrying at least one aryl substituent in a position adjacent to thephosphorus show a useful activity.

It is also known to use as catalyst complexes whose ligands are mutuallybridged. In particular, application WO 98/41529 discloses bridgedmonophospholyl complexes of the [α-SiMe₂(3,4,5-trimethylphosphole, NtBu]TiCl₂ type. In such complexes, the metal is linked to a phosphorus atomand to a nitrogen atom.

Application WO 98/01485 discloses monophospholyls of the type bridged bya donor-acceptor type link between the phosphorus and the boronP→B:[2,3,4,5-pentamethylphosphole,Me₂B-Cp]TiCl₂.

DESCRIPTION OF THE INVENTION

Biphospholyls bridged to the phosphorus by metals are also known (F.Nief et al., J. of Organometallic Chemistry 384, 1990, p. 271-78).

Heteroatom Chemistry, vol. 2, No. 3, 1991, pp 377-383, Deschamps et al.,discloses 1,1′-diphenyl-2,2′-thiophene-3,4,3′,4′tetramethyl-biphosphole. There is no disclosure of any use of saidcompound.

J. Chem. Soc., Perkin Trans. 1, 2000, 1519-1528, pp 1519-1528, Niemi etal. discloses 1,1′-diphenyl-2,2′ -vinylene-3,4,3′,4′ tetramethyl5,5′dibromo-biphosphole. There is no disclosure of any use of saidcompound.

Organometallics, 1991, vol. 16, No. 5, pp 1008-1015, gouygou et al.,discloses 1,1′-diphenyl-3,4,3′,4′ tetramethyl 2,2′-biphosphole znd itsuse for the synthesis of Ni, Pd and Pt-biphosphole complexes, thesecomplexes being disclosed as being useful for enantioselectivesynthesis.

WO-A-9850392 discloses monophosphole compounds bridged with acyclopentadienyle, indenyle ou fluorenyle cycle, optionally substituted.The disclosed application is alpha-olefines catalysis.

Organometallics, 2001, vol. 20, No. 8, pp 1499-1500, discloses synthesisof 1,1′-diphosphona[2]ferrocenophane, and as intermediates products the2,2′-ethylene-3,4,3′,4′ tetramethyl-biphosphole and1,1′-diphenyl-2,2′-ethylene-3,4,3′,4′ tetramethyl-biphosphole.Polymerization of diphosphona[2]ferrocenophane is disclosed. There isindeed no disclosure of any use of said intermediates products.

The object of the invention was therefore to produce novel catalysts inthe field of metallocenes or the like for single-site catalysis.

This invention relates to novel compounds of the bridged biphospholyltype, to novel catalytic metallocene compositions based on these bridgedbiphospholes and to their intermediates and preparation processes. Italso relates to processes for polymerizing olefins employing thesecatalytic components.

A first aspect of the invention therefore relates to bridgedbiphospholes that satisfy the general formula:

where:

R², R², R⁴ are chosen from hydrogen, alkyl, aryl or silyl;

R¹ is chosen from hydrogen, alkyl, aryl or halogen, R¹ possibly beingreplaced by a direct bond between the two phosphorus atoms and T is adivalent group.

The divalent group T may include a ring, preferably an aromatic ring, inparticular a benzene group.

Preferably, the divalent group T is a group satisfying the formula:

in which A is C, Si, ge or Sn;

R⁵ and R⁶ are, independently of each other, h, alkyl or aryl; and n isan integer from 1 to 10, preferably from 1 to 5.

Furthermore, if A is C, it will be possible for R⁵ and R⁶ to beconnected together so as to form with A a saturated or unsaturated ringhaving from 3 to 12 carbon atoms.

In the present description, the term “alkyl” will be understood to meana linear or branched hydrocarbon group containing 1 to 20 carbon atoms.The term “aryl” means an aryl group containing from 6 to 16 carbonatoms, possibly substituted with one or more alkyls containing from 1 to20 carbon atoms. The term “alkoxy” is understood to mean a substitutedor unsubstituted, linear or branched, ether group containing up to 20carbon atoms. The term “silyl” will be understood to mean a hydrocarbongroup containing silicon and up to 20 carbon atoms. The abbreviation“Cp” denotes the cyclopentadienyl ligand.

According to a preferred embodiment, A is a carbon atom and R⁵ and R⁶are a hydrogen atom.

A value of n of 2 is particularly preferred, especially if A is a carbonatom and R⁵ and R⁶ are a hydrogen atom. The bridge T then takes the formof ethylene.

According to one embodiment, bridge T is free of heteroatoms, especiallyfree of S, O and N.

According to one embodiment, bridge T is linear.

According to one embodiment, bridge T is saturated.

According to another embodiment, bridge T is unsaturated.

According to another embodiment, A is an Si, ge or Sn atom; R⁵ and R⁶are alkyl or aryl groups. When A is Si, ge, Sn, n is preferably equal to1.

According to one embodiment, the group T is located in the α positionwith respect to the phosphorus. The phosphorus atoms may then form adirect bond. According to another embodiment, the group T is located inthe β position with respect to the phosphorus.

Preferably, R², R³, R⁴ are chosen from hydrogen, methyl or phenyl. R¹ ispreferably phenyl or replaced with a direct bond between the phosphorusatoms.

Particularly preferred biphospholes according to the invention are1,1′-diphenyl-2,2′-ethylene-4,5,4′,5′ tetramethyl-biphosphole and2,2′-ethylene-4,5,4′,5′-tetraphenyl-1,1′-biphospholyl.

The bridged biphospholes according to the invention may be prepared byvarious processes. In particular, they may be obtained by the followingmethods:

-   -   “Würtz-type coupling” method, giving the α bridge;    -   “bis(zirconacyclopentadiene” method—this method allows α- or        β-bridge compounds to be obtained depending on the diyne used;        and    -   “copper-mediated oxidative coupling” method, giving the α        bridge.

According to a first embodiment, the invention provides a process forpreparing an α- or β-bridged biphosphole comprising the steps of:

-   -   coupling in the presence of magnesium metal of two phosphole        sulfides according to the following formula:        where R² to R⁴ are chosen from hydrogen, alkyl, aryl or silyl;

R¹ is a group chosen from hydrogen, alkyl, aryl or halogen;

R⁷ being chosen so as to form T after coupling; and

-   -   reduction of the bridged disulfide into the bridged biphosphole.

Preferably, the bridged disulfide is isolated and purified before thereduction is carried out.

According to a second embodiment, the invention provides a process forpreparing an α-bridged biphosphole comprising the steps of:

-   -   obtaining a bridged bis(alkenyl-chloro-zirconocene) by        hydrozirconation of a diyne with chlorohydrurozirconocene;    -   converting the bridged bis(alkenyl-chloro-zirconocene) into a        bridged bis(alkenyl-methyl-zirconocene);    -   decomposing the bridged bis(alkenyl-methyl-zirconocene) in the        presence of an alkyne; and    -   adding to the bridged bis(zirconacyclopentadiene) in solution an        organodihalogenophosphine in order to obtain a bridged        biphosphole.

According to a third embodiment, the invention provides a process forpreparing a β-bridged biphosphole, comprising the steps of:

-   -   metallization of a complexed phosphole with a lithium alkylamide        or silylamide into a complexed lithiomethylphosphole;    -   copper-mediated oxidative coupling of the complexed bridged        biphosphole using cupric chloride;    -   partial decomplexation by the action of sulfur into a bridged        biphosphole disulfide;    -   complete decomplexation by the action of cerium ammonium nitrate        (CAN) into a bridged disulfide; and    -   reduction to the biphosphole.

These bridged biphospholes may be used as transition metal ligands, inparticular for the preparation of metallocenes.

A second aspect of the invention therefore relates to metallocenesobtained from these bridged biphospholes. The general formula of thesemetallocenes is:

where R² to R⁴ and T are defined as above, M is a metal of groups III,IV, V, VI, VIII or of the series of lanthanides or the actinides.Preferably, M is zirconium or titanium, L is a halogen, hydrogen, alkyl,aryl or alkoxy and x is an integer ranging from 1 to 3. If M iszirconium or titanium, x is preferably equal to 2.

Among these metallocenes,1,1′-diphospha-2,2′-ethylene-4,5,4′5′-tetramethyl-dichlorozirconoceneand1,1′-diphospha-2,2′-ethylene-4,5,4′,5′-tetraphenyldichlorozirconoceneare particularly preferred.

The synthesis of the metallocene from the bridged biphosphole is carriedout via the bridged biphospholyl dianion:

This dianion may be prepared by cutting the P—R¹ bond or by cutting theP—P bond. Preferably, this cutting is accomplished by an alkali metal,such as lithium, sodium or potassium.

The metallocene can then be obtained by reacting the bridgedbiphospholyl dianion with a metal halide using one of the methods knownto those skilled in the art. The metallocene may thus be obtained bymaking the biphosphole with R¹=SiR₃ or SnR₃, R being an alkyl, reactwith a derivative of the metal M and preferably a halogenated derivativeof MX₄ type.

According to one embodiment, the process for preparing a metalloceneaccording to the invention then comprises the steps of:

-   -   conversion of a biphosphole according to the invention into a        dianion by cutting the P—R¹ or P—P bond; and    -   reacting the biphospholyl dianion with a halide of a metal from        groups III, IV, V, VI, VIII or possibly of the series of        lanthanides or actinides.

The metallocenes according to the invention can be used in particular ascatalytic component for the polymerization of olefins.

The third aspect of the invention therefore relates to a catalyticcomponent for polymerizing olefins. The metallocene may be employed byitself or in combination with other compounds. Preferably, themetallocene according to the invention is employed in combination with acocatalyst. Preferably the cocatalyst is an alumoxane (also calledaluminoxane). These compounds may be linear, of formula:

or cyclic, of formula:

where, in the two formulae, R may be identical or different andrepresents an alkyl radical having from one to six carbon atoms, and nbeing an integer ranging from 2 to 40, preferably from 10 to 20. Thealuminoxane may include R groups of different type. Moreover, it ispossible to employ mixtures of these compounds.

Preferably, a linear aluminoxane is employed. Among linear aluminoxanes,methyl aluminoxane or “MAO” in which each R is methyl is preferred.

The use of other cocatalysts, such as ionic cocatalysts, is alsopossible. Among these cocatalysts, mention may be made of compoundscontaining cations such as trimethyl ammonium, tributyl ammonium,N,N-dimethylanilinium, carbonium, oxonium or sulfonium. The anions arepreferably bulky and noncoordinating and may be, for example,tetraphenylborate, tetra(pentafluorophenyl) borate and anions containingmore than one boron atom.

Moreover, it may be advantageous to employ compounds capable of trappingimpurities, such as aluminum alkyls. Among aluminum alkyls,triisobutylaluminum (TiBA) is particularly preferred.

Moreover, the catalytic component may be employed in supported form, asis known to those skilled in the art. Such inert supports may be of anorganic or inorganic nature, such as, for example, silica gel, Al₂O₃,MgCl₂ or polymers. It is possible to deposit the metallocene and thecocatalyst on the support in succession—firstly the metallocene and thenthe cocatalyst or vice versa or at the same time. Preferably, thecocatalyst is deposited on the support, then the metallocene.

The catalyst composition according to the invention may be preparedaccording to a process comprising the steps of:

-   -   impregnating a catalyst support with a cocatalyst; and, before,        after or simultaneously,    -   impregnating this catalyst support with a metallocene according        to the invention.

A fourth aspect of the invention is a process for polymerizing olefins,in which the catalytic component according to the invention is broughtinto contact with at least one olefin monomer under conditions ofpolymerization with a catalyst composition according to the invention.

The polymerization process may be a homopolymerization orcopolymerization of one or more olefins, α-olefins, alkynes or diolefinsas monomers. Preferably, this is a process for polymerizing ethylene andbutene olefin monomers.

The polymerization processes are those conventionally used forpolymerizing olefins, such as gas phase polymerization, suspensionpolymerization, at high pressure, or else solution polymerization.

The ligand, the compounds obtained therefrom and their preparationaccording to the invention will be described below in greater detail bymeans of a few examples.

Ligand

The ligand according to the invention is formed from two unsaturatedphosphorous heterocycles called phospholes according to the IUPACnomenclature in force, these being substituted with various monovalentgroups and linked together by a divalent group, called hereafter a“bridge”.

The bridge may be located between the 2 position of one of the rings andthe 2′ position of the other ring (α bridge) or between the 3 positionof one of the rings and the 3′ position of the other ring (α bridge).This bridge is formed from a divalent group having one or more atoms(preferably 1 or 2) belonging to group IVb of the Periodic Table,preferably carbon or silicon, these being substituted with variousmonovalent groups.

The general formula of the ligand according to the invention, alsocalled bridged biphosphole, satisfies one of the three followingformulae. The numbering used is indicated below:

The groups R¹ to R⁶ may be monovalent organic groups such as: hydrogen,alkyl, aryl, silyl; the group R¹ may also be a halogen. In addition, inthe case of biphospholes bridged in the α position, there may be adirect bond between the two phosphorus atoms; these are then calledbridged 1,1′-biphospholyls.

Synthesis of the Ligands

Three general methods for synthesizing the bridged biphospholes aredescribed below.

(A) “Würtz Reaction”-Type Method

This method consists of Würtz-type oxidative coupling between twophosphole sulfides substituted in the α position by a brominated group.

This synthesis is explained by taking the Example of2-bromomethylphosphole according to the scheme below; it is particularlywell-suited for obtaining bridged biphospholes possessing an ethylenebridge in the α position. however, it is also possible to use this typeof coupling for substituted ethylene bridges of the CR¹R² CR³R⁴ type.

In this coupling reaction, two equivalents of a 2-bromomethylphospholesulfide are brought into contact with 1 to 5 equivalents, preferably 5equivalents, of magnesium metal in an ether solvent such astetrahydrofuran (THF) or dimethoxyethane (DME), THF being preferred. Themixture is left to react at a temperature of between 25° C. and 40° C.,preferably 35° C., for a time of greater than or equal to 2 hours,preferably 16 hours. The coupling product is then isolated andchromatographed on a silica gel column, with dichloromethane as eluent.

The bridged disulfide is then reduced to the bridged biphosphole. Thereduction may be obtained by the action of a tertiary phosphine such astributylphosphine or tri(cyanoethyl)phosphine, the latter beingpreferred. The reduction is preferably carried out at a temperaturegreater than or equal to 130° C., this being most easily achieved byreflux in xylene. The reaction is continued for a time of greater thanor equal to 2 hours, preferably 16 hours. The bridged biphospholeobtained is purified by recrystallization in methanol.

The 2-bromomethylphosphole sulfide required by the coupling reaction maybe conveniently obtained from 2-phosphole carboxyaldehyde. The lattermay be synthesized using the method described by E. Deschamps and F.Mathey, Bull. Soc. Chim. Fr. (1992), Vol. 129, p. 186.

The conversion of phosphole-2-carboxaldehyde to 2-bromomethylphospholesulfide requires three elementary steps:

-   a) reduction of phosphole-2-carboxaldehyde to    2-hydroxymethylphosphole: added to phosphole-2-carboxaldehyde    dissolved in an alcohol, preferably ethanol, is sodium borohydride,    preferably one equivalent, at a temperature of 0° C. or below,    preferably 0° C. The reaction mixture is brought back to 25° C. over    15 minutes; the 2-hydroxymethylphosphole thus obtained may be    isolated, but it is preferably kept in solution for the next step;-   b) passage from 2-hydroxymethylphosphole to 2-hydroxymethylphosphole    sulfide: the raw solution from the previous step is cooled to 0° C.    and added to this is one or more equivalents, preferably one    equivalent, of elemental sulfur, then stirred for 15 minutes or    longer, preferably 15 minutes and then brought back to room    temperature over 15 minutes or longer, preferably 15 minutes. The    solvent is evaporated and replaced with dichloromethane and then    this phase is washed with a solution of sodium chloride to neutral    pH, dried over magnesium sulfate and evaporated to dryness. The    2-hydroxymethylphosphole sulfide can then be purified by    chromatography, but it is preferably used as such for the purpose of    the next step;-   c) conversion of 2-hydroxymethylphosphole sulfide to    2-bromomethylphosphole sulfide: the raw 2-hydroxymethylphosphole    sulfide from the previous step is dissolved in dichloromethane in    the presence of one equivalent of triphenylphosphine. A solution of    one equivalent of dibromine in dichloromethane is then added drop by    drop for ten minutes (preferably) or longer, the temperature of the    reaction mixture being maintained between −20° C. and 0° C.    (preferably 0° C.). The addition is stopped when the solution has a    persistent yellow color, indicating that the dibromine is present in    excess. The solution is washed with an aqueous sodium sulfite    solution and evaporated to dryness under vacuum.    B) “Bridged bis(zirconacyclopentadiene)”-Type Method

In this method, the bridged biphospholes are obtained from bridgedbis(zirconacyclopentadienes) by the action of anorganodihalogenophosphine or a trihalogenophosphine in azirconium-phosphorus metathesis reaction; this metathesis also producesdichlorozirconocene as a byproduct. This reaction was described for thefirst time by Fagan with a symmetrical and unbridgedzirconacyclopentadiene (P. J. Fagan and W. A. Nugent, Journal of theAmerican Chemical Society, 1988, Vol. 110, p. 2310).

The general principle of synthesizing these zirconacyclopentadienes isthe oxidative coupling of two alkyne molecules about the zirconium. Tosynthesize bridged zirconacyclopentadienes, it is possible to adapt thepublished syntheses for unbridged zirconacyclopentadienes that use twodifferent alkynes. In our case, it is recommended to effect theoxidative coupling using an alkyne and a diyne according to thefollowing general scheme:

The difference in steric hindrance between the substituents on theacetylenes controls the regioselectivity of the coupling: bulky groupsbeing placed in the α position with respect to the zirconium, the bridgebeing in the α position if the T group is bulkier than R⁴ and in the βposition otherwise.

As an example, the method that was chosen is based on a study byBuchwald et al. (S. Buchwald and R. B. Nelsen, Journal of the AmericanChemical Society, 1989, Vol. 111, p. 2870). The reaction mixture is asfollows:

-   a) formation of a bridged bis(alkenyl-chloro-zirconocene) by    hydrozirconation of a diyne with chorohydridozirconocene (also    called Schwartz's reagent):

One equivalent of diyne and two equivalents of Schwartz's reagent aremade to react in a solvent (THF or dichloromethane) for about one hourat a temperature of less than or equal to 0° C.; the reaction isterminated when the solution is homogeneous. The bridgedbis(alkenyl-chloro-zirconocene) may be isolated, but it is preferablykept in solution for the purpose of the next step;

-   b) conversion of the bridged bis(alkenyl-chloro-zirconocene) to    bridged bis(alkenyl-methyl-zirconocene): added to the raw solution    from the previous step are two equivalents of methyllithium    dissolved in ether at −78° C. (the solvent then being THF) or methyl    magnesium bromide dissolved in ether at room temperature or below    (the solvent being THF or dichloromethane) and two equivalents of an    alkyne. The bridged bis(alkenyl-methyl-zirconocene) is not stable    and cannot be isolated;-   c) decomposition of the bridged bis(alkenyl-methyl-zirconocene) in    the presence of an alkyne: the previous solution is kept at room    temperature for at least two hours; over this time, the bridged    bis(alkenyl-methyl-zirconocene) decomposes with evolution of methane    and oxidative coupling takes place with the alkyne to give the    bridged bis(zirconacyclopentadiene). This complex may be isolated,    but it is preferably kept in solution for the purpose of    synthesizing the bridged biphosphole by the Fagan method:

A stoichiometric quantity of organodihalogenophosphine is added to thebridged bis(zirconacyclopentadienes) dissolved in dichloromethane(preferably), an ether or a hydrocarbon, in a temperature range from 0°to 60° C. over times varying from 30 minutes to 24 h depending on thesubstitution scheme: when the group R² is bulky, the reaction time willbe longer; it may also prove to be desirable, in this case to use atrihalogenophosphine, which is more electrophilic than adihalogenophosphine; a bridged 1,1′-biphospholyl will then be obtained.This synthesis will be illustrated by the examples of1,1′-diphenyl-2,2′-ethylene-4,5,4′,5′-tetramethyl-biphosphole and2,2′-ethylene-4,5,4′,5′-tetraphenyl-1,1-biphospholyl.

C) Copper-Mediated Oxidative Coupling

This method consists of oxidative coupling, via cupric chloride, of alithiomethylphosphole (a phosphole substituted with a —CH₂Li group), thelatter being obtained from a phosphole carrying a methyl group by directmetallization with a strong base (lithium amide). This method will bevery suitable for coupling in the β position; however, the scheme forsubstituting the initial phosphole preferably obeys the followingrelationships:

-   a) if R³ is a methyl, the two substituents R² and R⁴ are not alkyl    groups and are furthermore identical;-   b) if R³ is not a methyl, the three substituents R², R³ and R⁴ are    not alkyl groups, but may be different.

To increase the acidity of the methyl group in the 3 position of thephosphole and therefore to facilitate the direct metallization with astrong base, the two double bonds will be complexed by a(tricarbonyl)iron group and the lone pair of the phosphorus by a(tetracarbonyl)iron group, which also act as protective groups: thesecomplexed phospholes may be synthesized as described by F. Mathey and g.Muller, Journal of Organometallic Chemistry, 1977, Vol. 136, p. 241).

The bridged biphospholes are obtained in five steps:

-   a) metallization of the complexed phosphole: added to the complexed    phosphole, dissolved in THF, undergoes the addition at a temperature    not exceeding −80° C. is one equivalent of a lithium alkylamide or    silylamide (preferably lithium diisopropylamide); the addition lasts    about ten minutes; the complexed lithiomethylphosphole obtained is    kept dissolved at low temperature for the purpose of the next step;-   b) actual copper-mediated oxidative coupling: one equivalent of    cupric chloride is added at a temperature not exceeding −80° C. to    the complexed lithiomethylphosphole obtained in the previous step.    The reaction mixture is then brought back to room temperature over    one hour, the solvent evaporated to dryness and the residue    chromatographed on a silica column: a complexed bridged biphosphole    is thus obtained;-   c) partial decomplexation by the action of sulfur: the complexed    bridged biphosphole obtained in the previous step is dissolved in    toluene or xylene and 4 to 5 equivalents of elemental sulfur are    added. The reaction mixture is taken to reflux from 1 to 2 hours,    then evaporated to dryness and the residue chromatographed on a    silica column. the product obtained is a complexed bridged    biphosphole disulfide;-   d) total decomplexation by the action of cerium ammonium nitrate    (CAN): the complexed bridged biphosphole disulfide is dissolved in a    1/1 dichloromethane/isopropanol mixture and 4.5 equivalents of CAN    are added. After 45 minutes of reaction, the reaction mixture is    hydrolyzed and the solution is extracted with dichloromethane. The    bridged biphosphole disulfide obtained is purified by chromatography    on a silica column;-   e) conversion of the bridged biphosphole disulfide into a bridged    biphosphole: this reaction may be carried out under the same    conditions as those described in A in the case of the α-bridged    biphosphole.    Conversion into a Complex

The conversion of the ligand into a zirconium complex, denoted as“ansadiphosphadichloro-zirconocene” generally involves the followingseries of reactions:

-   -   1) cutting of the P—R¹ or P—P bonds of the ligand, preferably by        an alkali metal—lithium, sodium or potassium—in a polar solvent        such as, for example, tetrahydrofuran, with the formation of        bridged biphospholyl dianions:    -   2) Reaction of these bridged biphospholyl dianions with        zirconium tetrachloride to give the corresponding        ansadiphosphadichlorozirconocenes:

The general operating method for synthesizing theansadiphosphadichlorozirconocenes is not fundamentally different thanthat of the other diphosphadichlorozirconocenes—reference may be made tothe methods described in WO 95/04087. This synthesis will be illustratedby the example of the preparation of1,1′-diphospha-2,2′-ethylene-4,5,4′,5′-tetramethyldichloro-zirconoceneand1,1′-diphospha-2,2′-ethylene-4,5,4′,5′-tetraphenyldichlorozironocene.

The invention is illustrated by the following examples, without itsscope being limited to them.

EXAMPLES Examples of Synthesis of Ligands Example 1 Synthesis of1,1′-diphenyl-2,2′-ethylene-4,5,4′5′-tetramethylbiphosphole

5 ml of 1,5-hexadiyne (26.6 mmol) were added to a suspension of 13.74 g(53.2 mmol) of Schwartz's reagent in 100 ml of freshly distilleddichloromethane in a Schlenk tube under argon cooled to 0° C. TheSchwartz's reagent gradually dissolved as it reacted over about onehour. The solution turned a clear light yellow.

2.87 g of 2-butyne (53.2 mmol) and then methylmagnesium bromide (53.2mmol) were added, again at 0° C. A pale red solution was obtained, towhich about twelve milliliters of THF were added in order to completelydissolve the grignard reagent. After a few minutes, the formation ofinsoluble magnesium salts again opacified the reaction mixture.

After stirring overnight at room temperature, dichlorophenylphosphine(7.2 ml, i.e. 53.2 mmol) were added to the reaction mixture cooled to 0°C.

Next, the reaction mixture was filtered and then the precipitate waswashed with dichloromethane. After the combined organic phases hadevaporated, the residue was extracted with toluene and then evaporatedto dryness, the extraction/evaporation operation being repeated withether and possibly with pentane.

The 5.11 g (48%) of1,1′-diphenyl-2,2′-ethylene-4,5,4′,5′-tetramethylbiphosphole thusobtained were recrystallized cold in methanol.

Example 2 Synthesis of1,1′-diphospha-2,2′-ethylene-4,5,4′5′-tetramethyldichloro-zirconocene

A solution of 480 mg (12 mmol) of1,1′-diphenyl-2,2′-ethylene-4,5,4′5′-tetramethylbiphosphole in 20 ml offreshly distilled THF was brought into contact with 34 mg (48 mmol) oflithium pieces in a Schlenk tube under argon. The solution darkened andthe presence of the bridged biphospholyl dianion was confirmed by ³¹PNMR. When there was no longer any biphosphole (after about one hour),about one hundred milligrams of aluminum trichloride (0.8 mmol) wereadded and the mixture left to stir for one quarter of an hour untilcomplete dissolution.

The zirconium tetrachloride solvated by two molecules of tetrahydrofuran(ZrCl₄.2THF:450.5 mg; 12 mmol) was added as such to the bridgedbiphospholyl dianion solution. The complex formed immediately. Twodiastereoisomers (2/3 of meso according to ¹H NMR) were obtained. Afterthe THF was evaporated, the bridged diphosphazirconocenes were washedwith dichloromethane, then with toluene and, finally, recrystallized inpentane. 180 mg of1,1′-diphospha-2,2′-ethylene-4,5,4′,5′-tetramethyldichlorozirconocenewere obtained in the form of yellow crystals (37%). No enrichment of oneor other of the isomers was observed. In fact, an X-ray diffractioncrystallographic study showed that these crystallize with the same unitcell.

Example 3 Synthesis of2,2′-ethylene-4,5,4′5′-tetraphenyl-1,1′-biphospholyl

1.51 g of 1,5-hexadiyne (19.3 mmol) were added to a suspension of 10 g(38.6 mmol) of Schwartz's reagent in 120 ml of freshly distilleddichloromethane in a Schlenk tube under argon, cooled to 0° C. When thesolution had become homogeneous, the solvent was evaporated and then thehydrozirconation product was taken up in tetrahydrofuran (120 ml) andthe reaction mixture cooled −78° C. Methylmagnesium bromide (14.6 ml;38.6 mmol) was added drop by drop and then the solution was stirred,cold, for a quarter of an hour. A small amount of trimethylsilylchloride (0.21 ml; 1.7 mmol) was introduced to trap any unreactedgrignard reagent and then, after one minute, diphenylacetylene (6.9 g;38.6 mmol) dissolved in 5 ml of tetrahydrofuran was added. The coolingbath was removed and the solution was stirred at room temperature for 24hours. The evolution of methane could be seen and the reaction mixturegradually turned an intense red color.

Phosphorus trichloride (3.38 ml; 38.6 mmol) was added at 0° C., and thenthe reaction mixture taken to room temperature over 16 hours.1,1′-biphospholyl partly precipitated; the solution was filtered and theyellow solid collected was washed with hexane and optionally purified bysuccinct chromatography on silica gel with a dichloromethane/hexane(10/90) mixture as eluent. The filtrate was evaporated to dryness, takenup in dichloromethane, filtered over a glass frit and thenchromatographed on silica gel. The excess diphenylacetylene was firstlyeluted with hexane and then the 1,1′-biphospholyl was eluted with adichloromethane/hexane (10/90) mixture. 3.27 g of2,2′-ethylene-4,5,4′,5′-tetraphenyl-1,1′-biphospholyl were thus obtained(35%). The 1,1′-biphospholyl was able to be recrystallized in ahexane/dichloromethane mixture by slowly evaporating thedichloromethane.

Example 4 Synthesis of1,1′-diphospha-2,2′-ethylene-4,5,4′5′-tetraphenyldichlorozirconocene

A solution—suspension of2,2′-ethylene-4,5,4′5′-tetraphenyl-1,1′-biphospholyl (248 mg; 0.5 mmol)in tetrahydrofuran (6 ml)—was made to react with excess lithium at roomtemperature in a Schlenk tube under argon. The solution turned a deepred color as the phospholyl anion formed. When the 1,1′-biphospholyl hadbeen entirely consumed, according to ³¹P NMR, the solution was addeddrop by drop to a suspension, cooled to 0° C., of ZrCl₄.2THF (189 mg;0.5 mmol) in 9 ml of dry toluene. The reaction mixture was stirred at 0°C. for 20 minutes. The crude reaction mixture was stripped of its saltsby filtration in dichloromethane. The diphosphadichlorozirconocene wasobtained in the form of a pair of diastereoisomers (1:2 in favor of themeso-isomer according to ¹³C and ³¹P NMR), and its formation wasaccompanied by that of a small amount of 1,1′-biphospholyl (1:15). Thecomplex partly precipitated when 5 ml of hexane were added to a solutionof the mixture in 10 ml of toluene. The solution was filtered and thezirconocenes then crystallized slowly in the filtrate. The actual1,1′-diphospha-2,2′-ethylene-4,5,4′,5′-tetraphenyldichlorozirconocenewas obtained with an 80% yield.

Examples of the Synthesis of Supported Catalysts Example 5 Preparationof Catalytic Component C1

10 g of SYLOPOL 21-04 silica supplied by grace, that had been dehydratedbeforehand by treatment at 200° C., were placed in a clean, dry 200 mlreactor purged with nitrogen then 50 g of a 10 wt % solution of MAO intoluene were added at room temperature. The mixture was taken to refluxfor 4 h and then the toluene was removed by filtration. The solid S1 waswashed twice with 50 ml of toluene and 50 ml of hexane, then dried at50° C. under a dry nitrogen purge.

10 g of the solid S1 were placed under nitrogen in a clean, dry 500 mlreactor, followed by a suspension of 90 mg of the compound synthesizedin Example 2 in 200 ml of dry hexane. The mixture was heated to 60° C.with stirring for 1 hour. The suspension was filtered and the solidwashed twice with 100 ml of hexane at 45° C. The solid C1 obtained wasdried at 65° C. It contained 0.26% Zr and 14.1% Al.

Example 6 (Comparative Example) Preparation of Catalytic Component C2

The operating method for Example 5 was repeated, the 90 mg of compoundsynthesized in Example 2 being replaced with 100 mg ofbis(2,3,4,5-tetramethylphospholyl)dichlorozirconocene synthesizedaccording to the procedures known from the literature (see, for example,Boer et al. in J. Mol. Cat., A: Chem. 128(1998), 155-165 or Janiak etal. in J. Org. Chem. 501(1995), 219-224). The solid C2 thus obtainedcontains 0.2% Zr and 14.7% Al.

Examples of Polymerization Example 7 Application of Catalytic ComponentC1 in the Copolymerization of Ethylene with Butene

1.4 bar of butene and 13.5 bar of ethylene were introduced at 75° C.into an 8-1 spherical polymerization reactor, provided with stirring andwith temperature regulation, and containing 100 g of polymer producedduring a prior trial carried out under the same conditions. Next, 110 mgof TiBA and 100 mg of catalytic component were injected via an airlockand via the thrust of pressurized dry nitrogen. The total pressure inthe reactor was kept at 21 bar absolute for 4 hours with stirring,feeding the reactor continuously with a mixture of ethylene and butenein a butene/ethylene molar ratio of 0.046. After 4 hours, the polymerwas isolated and weighed. The productivity determined by weighing thepolymer was 2800 g of PEBdL/g/catalyst. The melt index under 2.16 kg(MI₂) was not measurable, the polymer being too viscous, the density was0.930 and the butene content of the polymer was 1.3% by weight.

Example 8 This Example was produced under the same conditions, but withcatalytic compound C1 substituted with component C2

Example 7 illustrates the invention; Example 8 is comparative.

The results of the evaluation of the ethylene-butene copolymerizationcatalysts are given in the table below.

Productivity Productivity Catalyst (g/g_(cat)) (g/g_(Zr) × 10⁻⁶) MI D %Butene C1 2800 1.400 nm* 0.930 1.3 C2 330 0.165 / / / (comparative) *notmeasurable as the polymer viscosity was too high.

It may be seen that, for ethylene/butene copolymerization, theactivities obtained are better in the case of the bridged biphosphole C1compared with an unbridged biphosphole (C2).

Although the invention has been described in conjunction with specificembodiments, it is evident that many alternatives and variations will beapparent to those skilled in the art in light of the foregoingdescription. Accordingly, the invention is intended to embrace all ofthe alternatives and variations that fall within the spirit and scope ofthe appended claims. The foregoing references are hereby incorporated byreference.

1. A bridged biphosphole according to the formula:

where: R², R³, R⁴ are selected from hydrogen, alkyl, aryl or silyl; R¹ is selected from hydrogen, alkyl, aryl or halogen, R¹ possibly being replaced by a direct bond between the two phosphorus atoms; and T is a divalent group with the exclusion of the component 1,1′-diphenyl-2,2′-thiophene-3,4,3′,4′tetramethyl-biphosphole.
 2. The bridged biphosphole as claimed in claim 1, wherein the divalent group T is a group according to the formula:

in which A is C, Si, Ge or Sn; R⁵ and R⁶ are, independently of each other, H, alkyl or aryl; and n is an integer from 1 to
 10. 3. The bridged biphosphole as claimed in claim 2, wherein A is a carbon atom and R⁵ and R⁶ are a hydrogen atom and n is equal to
 2. 4. The bridged biphosphole as claimed in claim 2, wherein A is an Si, Ge or Sn atom and R⁵ and R⁶ are alkyl or aryl groups.
 5. The bridged biphosphole as claimed in claim 2, wherein A is Si, Ge or Sn and n is equal to
 1. 6. The bridged biphosphole as claimed in claim 1, wherein the divalent group T includes a ring.
 7. The bridged biphosphole as claimed in claim 6, wherein the ring is an aromatic ring.
 8. The bridged biphosphole as claimed in claim 7, wherein the aromatic ring is a benzene ring.
 9. The bridged biphosphole as claimed in claim 1, wherein the group T is located in the α position with respect to the phosphorus.
 10. The bridged biphosphole as claimed in claim 9, wherein the phosphorus atoms form a direct bond.
 11. The bridged biphosphole as claimed in claim 1, wherein the group T is located in the β position with respect to the phosphorus.
 12. The bridged biphosphole as claimed in claim 1, wherein R², R³, R⁴, are selected from hydrogen, methyl or phenyl.
 13. The bridged biphosphole as claimed in claim 1, wherein R¹ is phenyl or is replaced with a direct bond between the phosphorus atoms.
 14. The bridged biphosphole as claimed in claim 1, wherein the biphosphole is selected from 1,1′-diphenyl-2,2′-ethylene-4,5,4′,5′tetramethyl-biphosphole and 2,2′-ethylene-4,5,4′,5′-tetraphenyl-1,1′-biphospholyl.
 15. A process for preparing a bridged biphosphole as claimed in claim 1, comprising: coupling in the presence of magnesium metal of two phosphole sulfides according to the following formula:

where: R² to R⁴ are selected from hydrogen, alkyl, aryl or silyl; R¹ is a group selected from hydrogen, alkyl, aryl or halogen; R⁷ is selected to form T after coupling; and reduction of the bridged disulfide obtained into the bridged biphosphole.
 16. A process for preparing a bridged biphosphole as claimed in claim 1, comprising: obtaining a bridged bis(alkenyl-chloro-zirconocene) by hydrozirconation of a diyne with chlorohydrurozirconocene; converting the bridged bis(alkenyl-chloro-zirconocene) into a bridged bis(alkenyl-methyl-zirconocene); decomposing the bridged bis(alkenyl-methyl-zirconocene) in the presence of an alkyne; and adding to the bridged bis(zirconacyclopentadiene) in solution an organodihalogenophosphine to obtain a bridged 1,1′-biphospholyl.
 17. A process for preparing a bridged biphosphole as claimed in claim 11, comprising: metallization of a complexed phosphole with a lithium alkylamide or silylamide into a complexed lithiomethyiphosphole; copper-mediated oxidative coupling of the complexed bridged biphosphole using cupric chloride; partial decomplexation by the action of sulfur into a bridged biphosphole disulfide; complete decomplexation by the action of cerium ammonium nitrate (CAN) into a bridged disulfide; and reduction to the biphosphole.
 18. A metallocene according to the formula:

where: R², R³, and R⁴ are selected from hydrogen, alkyl, aryl or silyl; T is a divalent group; M is a metal from Groups III, IV, V, VI, VIII or from the series of lanthanides or actinides; L is a halogen, a hydrogen, an alkyl, an aryl or an alkoxy; and x is an integer ranging from 1 to
 3. 19. The metallocene as claimed in claim 18, wherein the divalent group T is a group according to the formula:

in which A is C, Si, Ge or Sn; R⁵ and R⁶ are, independently of each other, H, alkyl or aryl; and n is an integer from 1 to
 10. 20. The metallocene as claimed in claim 19, wherein A is a carbon atom and R⁵ and R⁶ are a hydrogen atom and n is equal to
 2. 21. The metallocene as claimed in claim 19 wherein A is an Si, Ge or Sn atom and R⁵ and R⁶ are alkyl or aryl groups.
 22. The metallocene as claimed in claim 19, wherein A is Si, Ge or Sn and n is equal to
 1. 23. The metallocene as claimed in claim 18, wherein M is zirconium or titanium and x is equal to
 2. 24. The metallocene as claimed in claim 23, wherein it is 1,1′-diphospha-2,2′-ethylene-4,5,4′,5′-tetramethyl-dichlorozirconocene.
 25. A process for preparing a metallocene as claimed in claim 18, comprising: conversion of a biphosphole according to the general formula:

where: R², R³, R⁴ are chosen from hydrogen, alkyl, aryl or silyl; R₁ is chosen from hydrogen, alkyl, aryl or halogen, R¹ possibly being replaced by a direct bond between the two phosphorus atoms; and T is a divalent group; in which R², R³, R⁴ and T are as claimed in claim 1, into a dianion by cutting the P—R¹ or P—P bond; and reacting the biphospholyl dianion with a halide of a metal from Groups III, IV, V, VI, VIII or optionally of the series of lanthanides or actinides.
 26. A process as claimed in claim 25, wherein the bridged biphosphole R¹ is a phenyl or is replaced by a direct bond between the two phosphorus atoms.
 27. A catalyst composition comprising a metallocene as claimed in claim
 18. 28. The catalyst composition as claimed in claim 27, further comprising an aluminoxane and/or a substantially noncoordinating anion as cocatalyst.
 29. The catalyst composition as claimed in claim 27, supported on an inert catalyst support.
 30. A process for preparing the catalyst composition as claimed in claim 27, comprising: impregnating a catalyst support with a cocatalyst; and, before, after or simultaneously, impregnating this catalyst support with a metallocene as claimed in claim
 18. 31. A process for polymerizing olefins, comprising bringing at least one olefin monomer under polymerization conditions into contact with a catalyst composition as claimed in claim
 27. 32. The process as claimed in claim 31, wherein the olefin monomers are ethylene and butene.
 33. The metallocene as claimed in claim 18, wherein the divalent group T includes a ring.
 34. The metallocene as claimed in claim 33, wherein the ring is an aromatic ring.
 35. The metallocene as claimed in claim 34, wherein the aromatic ring is a benzene ring.
 36. The metallocene as claimed in claim 18, wherein the group T is located in the α position with respect to the phosphorus.
 37. The metallocene as claimed in claim 36, wherein the phosphorus atoms form a direct bond.
 38. The metallocene as claimed in claim 18, wherein the group T is located in the β position with respect to the phosphorus.
 39. The metallocene as claimed in claim 18, wherein R², R³, R⁴, are selected from hydrogen, methyl or phenyl.
 40. A process for preparing a bridged biphosphole as claimed in 1,1′-diphenyl-2,2′-thiophene-3,4,3′,4′tetramethylbiphosphole, comprising: obtaining a bridged bis(alkenyl-chloro-zirconocene) by hydrozirconation of a diyne with chlorohydrurozirconocene; converting the bridged bis(alkenyl-chloro-zirconocene) into a bridged bis(alkenyl-methyl-zirconocene); decomposing the bridged bis(alkenyl-methyl-zirconocene) in the presence of an alkyne; and adding to the bridged bis(zirconacyclopentadiene) in solution an organodihalogenophosphine in order to obtain a bridged 1,1′-biphospholyl. 